Air enters a compressor at ambient conditions of 100 kPa and 23 °C and leaves at 800 kPa. Heat is lost from the compressor in the amount of 120 kJ/kg with a boundary temperature of 40 °C. The air experiences an entropy decrease of 0.4 kJ/kg-K. Assume constant specific heats (cv = 0.721 kJ/kg·K; c, = 1.005 kJ/kg-K). The gas constant for air is 0.287 kJ/kg-K. Determine: a) Three valid assumptions (besides constant specific heats) b) Exit temperature of air (°C) c) Entropy generation during this process (kJ/kg-K)

Air enters a compressor at ambient conditions of 100 kPa and 23 °C and leaves at 800 kPa. Heat is lost from the compressor in the amount of 120 kJ/kg with a boundary temperature of 40 °C. The air experiences an entropy decrease of 0.4 kJ/kg-K. Assume constant specific heats (cv = 0.721 kJ/kg·K; c, = 1.005 kJ/kg-K). The gas constant for air is 0.287 kJ/kg-K. Determine: a) Three valid assumptions (besides constant specific heats) b) Exit temperature of air (°C) c) Entropy generation during this process (kJ/kg-K)

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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Concept explainers

Work and Heat Transfer

It is generally related to thermal engineering which tells about the use, creation, conversion and transfer of heat energy between the systems. It is also considered that to transfer heat from one source to another, transfer of masses is also required. There are various mechanisms by which, transfer of heat takes place i.e. thermal conduction, convection, radiation or by change of phase. All these mechanisms have their own specific features which sometimes occur simultaneously within the same system.

Question

Air enters a compressor at ambient conditions of 100 kPa and 23 °C and leaves at
800 kPa. Heat is lost from the compressor in the amount of 120 kJ/kg with a boundary
temperature of 40 °C. The air experiences an entropy decrease of 0.4 kJ/kg-K. Assume constant
specific heats (cy = 0.721 kJ/kg-K; c, = 1.005 kJ/kg-K). The gas constant for air is 0.287 kJ/kg-K.
Determine:
a) Three valid assumptions (besides constant specific heats)
b) Exit temperature of air (°C)
c) Entropy generation during this process (kJ/kg-K)

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